Many vehicle seats are of a type enabling position adjustment of plural portions so as to suit the build and posture of an occupant, the position adjustment includes, for example, sliding the overall seat in the front-rear direction, moving the height of the seat face up and down, or reclining the seatback (backrest). Such adjustment of the plural movable portions may be performed manually, however more convenient electric seats are provided that use the drive of a motor to perform adjustments.
In order to independently drive respective movable portions, a configuration wherein motors are individually coupled to respective drive shafts that are each coupled to a movable portion may be considered, however this would increase the number of motors. Since it is more efficient for a single motor to drive plural output shafts, proposals have been made wherein the power of a motor is transmitted through clutches to respective output shafts coupled to the plural movable portions, and each of the movable portions is selectively driven by connecting and disconnecting the clutches (see for example Japanese Patent Application Laid-Open (JP-A) No. H6-156123). Such known multi-shaft drive devices include driven side bevel gears respectively provided to plural output shafts so as to be capable of moving in the axial direction. The driven side bevel gears are provided in a biased state capable of enmeshing with drive side bevel gears on a motor shaft. The driven side bevel gears are moved towards and away from the drive side bevel gears by cams that press the driven side bevel gears, thereby switching between power transmission paths (Japanese Utility Model Publication (JP-Y) No. S54-41898).    Patent Document 1: Japanese Patent Application Laid-Open (JP-A) No. H6-156123    Patent Document 2: Japanese Utility Model Publication (JP-Y) No. S54-41898